QRS Fragmentation and Sudden Cardiac Death in the Obese and Overweight

BACKGROUND: Obesity has been associated with significantly greater risk of sudden cardiac death (SCD); however, identifying the obese patient at highest risk remains a challenge. We evaluated the association between QRS fragmentation on the 12-lead electrocardiogram and SCD, in obese/overweight subjects. METHODS AND RESULTS: In the ongoing prospective, community-based Oregon Sudden Unexpected Death Study (population approximately 1 million), we performed a case-control analysis, comparing obese/overweight SCD victims with obese/overweight controls from the same geographic region. Archived ECGs prior and unrelated to the SCD event were used for cases and all ECG measurements were assessed in blinded fashion. Fragmentation was defined as the presence of RSR' patterns and/or notching of the R/S wave in at least 2 contiguous leads. Analysis was limited to ECGs with QRS duration <120 ms. Overall prevalence of fragmentation was higher in cases (n=185; 64.9±13.8 years; 67.0% male) compared with controls (n=405; 64.9±11.0 years; 64.7% male) (34.6% versus 26.9%, P=0.06). Lateral fragmentation was significantly more frequent in cases (8.1% versus 2.5%; P<0. 01), with non-significant differences in anterior and inferior territories. Fragmentation in multiple territories (≥2) was also more likely to be observed in cases (9.7% versus 4.9%, P=0.02). In multivariable analysis with consideration of established SCD risk factors, lateral fragmentation was significantly associated with SCD (OR 2.84; 95% CI 1.01 to 8.02; P=0.05). CONCLUSION: QRS fragmentation, especially in the lateral territory is a potential risk marker for SCD independent of the ejection fraction, among obese/overweight subjects in the general population.